The present invention relates to a hipot barrier structure for a transformer, and more particularly to an insulating barrier member having substantially C-shaped cross-section for tightly fitting onto a high-tension side of a core of the transformer. The barrier member forms an outer layer at the high-tension side of the core to increase a creepage distance between the core and pins on the transformer located closely to the core, so that hipot, if any, would not directly flow across the core from the adjacent pins.
It is known that transformers are required components in an electronic circuitry. With the even thinner, lighter and compact volume designed for existing circuit boards, the transformers are also designed to meet the requirement of miniaturization. Meanwhile, there are different safety codes for different electronic parts used for different purposes. Only those qualified and certified electronic parts can be used to protect other components in the same circuitry. Among the American and European electronic safety codes adopted by all countries in the world, there is one safety code about grades of creepage distance between the pin and the core of a transformer. The creepage distance is defined by the length of a line extending along a surface of a bobbin of the transformer between an end of the pin connected to the bobbin and one side of the core adjacent to the pin. Such creepage distance differs with different grades under the safety code, but there is always a minimum safety distance specified by the codes. When a creepage distance is smaller than a specified safety grade, it means the distance between the pin or pins and the core is too short to prevent a hipot, which might occur, for example, at a lightning, from transmitting from the pins at a high-tension side to the pin or pins connected to the other side (or the low-tension side) of the bobbin by directly crossing over the core, and would therefore cause damage to other components in the circuitry.
It is necessary to solve the problem of short creepage distance between the core and the adjacent pins in the transformer to meet the safety code and avoid damage caused by hipot directly crossing over the core.